View Full Version : electric jet drives as auxillery drives

11-25-2006, 10:04 AM
I didn't want to post this until I at least had working jets but just to clarify. whats being done heres it be.
Its pretty simple. A front shell that meets the transom at the correct angle. An intake section, impellor, stator, nozzle and reversing bucket controlled by a pneumatic ram. The bucket not only provides reverse but neutral with the motors still running... like a jet!

This is one of those its a my problem not a your problem. I have to travel through shallow water and am somewhat lousy at docking. I also don't like clunking my motor back and forth from reverse to forward or idling with it down channels to get to the lake. There are no ramps on the lake although one ramp is very close to it, the others are not. Shallow water means you trim the prop up so high your pushing the stern down anyway. Your prop is safe but your LWP are now vacuum cleaners sucking up mud or sand and it stays in the heads.There are also tiny ones like not smogging out a resturant as I'm pulling up to it. Or spraying myself by putting the thing in reverse.

And as a why not figured to use them while on plane to recharge the battery. I've dumped that idea since its too complex electrically. The motors would spin too fast and supply way too much amps too quickly.
This is the scooping idea for the jet. Much harder to make and more crap on the transom, not to mention the loading increase on the transom.

I began with the idea of using props but stumbled on using tiny jets instead.
With props they are fairly large and ugly but mostly need a very expensive speed controler a PWM, with reverse and x 2 drives at high amperage $$$$.
Jets on the other hand don't reverse the electric motor and speed is simply controlled by how much reverse bucket is hanging in the stream. And I can crab the boat sideways too.

2 are being used on the sponsons so the wide drive displacement is the steering. I was going to use 2- 2.5 hp 12v motors but gave that up as too hoggish on the battery.Besides they are heavy, almost as heavy as starter motors. Now am using 2- 1.5 hp motors so thats either .6 hp on 12 volts or 3 hp on 24v. A simple speed control just with that alone.
I don't expect the batteries to supply me with much time but if I want to take a slow cruise around the pond I should be able to do silently with no eye burning smog blowing past me... for a little while.;) After all how long can you take a few MPH?

BTW there are model jet drives for of course RC models. Most are tiny plastic peices of garbage but one is (was) made from aluminum and takes a much larger engine. What I'm making are not model jets drives since the intake is all wrong. They are auxillery drives for me, cause I like my cake and eat it too.:rolleyes:

11-30-2006, 08:33 PM
Tecknow.they have had electric jet's for thrusters for 40 yr's, in all sizes the last 25. I think you've got jet fever which can be addicting to non users and can have sever side effect's like abdominal and rib pains due to jab's from propeller drivin outboard egos.Don't let this get out of hand and gain too much power or you may just cross the line of power and it were to ever become Full Blown you may go into a phucum state.YOU COULD GO INBOARD,I MEAN OVERBOARD. Please be careful.:cool:

11-30-2006, 10:18 PM
dude just put a hydraulic jackplate on your boat set it so your running hieght is closest to the bottom as possible then , jack it all the way up and then run the motor down and avoid all the vaccum effect and stern drop ect... will cut less water reducing draft anyway... jets are a waste... add weight increase draft (not what your trying to do.. )..

The Big Al
11-30-2006, 10:33 PM
Why reverser at end of jet??

Electric DC motor! Just reverse the motor!

I would like to have one for a RC boat!

That would be fun!

11-30-2006, 10:43 PM
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11-30-2006, 10:44 PM
there ya go Al...

BTW you cant reverse a jet drive, they only work one way.

12-04-2006, 07:49 PM
Racemore. They may have them but I found none. They are probably just as expensive as a full sized unit too! I will have inboards and will be able to brag with the jet crowd about my twin drive system:rolleyes: I will have triple drive in fact. :D

150aintenuff. With hydraulic jackplates running the $$ they do I have better things to spend the money on. I'm still split on whether to leave my manual off and this would mean I couldn't use a hydralic since it WEIGHS too much and sets back more than zero. Both of these also dumps the stern even more and is lifting the bow even more.
I'm talking about a manual that had the shaft above the bottom. How much higher you want me to go.;) ("To the moon alice. To the moon"):D
Jets never increase draft they decrease it, since mine will be mounted above the floor they will be above the bottoms of the sponsons. I haven't wieghed it yet but 4lbs? 10? My boat already weighs almost 200 lbs less than a regular STV so... no biggy.

The Big Al. The reverser is the biggest reason for dumping props. If you want reverse you must reverse the motor and that aint all that easy even without speed control. Add speed control and your talking hydraulic jack plate costs. I could build the massive switchs that could handle it but this gives me little in the way of manuevering. On or Off but nothing in between.

1BadAction. First $170 time 2 = $340 Too much. Second I don't know the powers mentioned but think they are way less than a 1.5 hp motor. Third how do I mount these to my transom? Where does the motor go? These are miniture jet drives not auxillery drives. I had considered it but starting a glow plug underwater was out of the question.

and you can reverse a jet. Why you would want to do this on an inboard mega hp one with a gear box I don't know. But you can reverse the pump, its a lousy pump but still in suction, or you can use a thrust reverser, that thing on the back of the picture you showed.:)

Maybe I shouldn't mention this but with the electric drives with a PWM controller still left the me the problem of controlling the things. I considered an RC system which would mean I could pilot the boat and not even be in it... a full scale model. But too pricey. Too pricey but not insane.

12-04-2006, 09:36 PM
good luck building your own for less than 340.00...

12-04-2006, 10:01 PM
Why reverser at end of jet??

Electric DC motor! Just reverse the motor!

I would like to have one for a RC boat!

That would be fun!

Won't work, there would be no thrust in a direction that would move the boat backwards.

12-16-2006, 08:39 PM
12" mid...... the jets wont work.. especially when you fly the boat on plane.. did you think of the fact that the intakes will allow a vaccum under the hull causing it to hold water longer and the added water flow at speed may blow out the jets filling the boat with water.... Just trim the motor up or buy a jet boat...

12-22-2006, 06:15 PM
The jets will work otherwise I wouldn't waste my time building them.:eek:
The drawing way up top shows a totaly external jet that will be mounted just below deck level. They mount to the transom and the intake is just under the tubular part thats slashed green. The only thing in the boat is the electric motor running it.
Its in the water off plane but no where near the water even at 30 mph.
They won't work on plane, theys is out of the water totally.
Thats why I said
What I'm making are not model jets drives since the intake is all wrong. They are auxillery drives for me

It don't matter how short the mid is since its where the prop is that matters. Like the bottom of the boat:rolleyes: Lowering the motor don't make the water deeper.
Jets are too slow and heavy. Trimming the motor up means paddling. I ain't no kayaker.:)
And they won't let me go through these areas on plane which would make the water deep enough... go figure.